The purpose of this five year randomized trial of a neighborhood based comprehensive day treatment for 300 pregnant illicit drug users is to determine whether random assignment to a program including treatment for addiction, pre and post-partum maternal medical care, nutrition counseling, vocational training, family support, and pediatric care for the infant over the first two years of life will bave, when compared to 300 control women who receive standard care: decreased drug use; increased number of prenatal visits; improved perinatal outcome including a lower incidence of adverse pregnancy complications and improved neonatal outcome for the infant; increased retention rate in drug addiction treatment; decreased adverse health behaviors such as drinking, smoking cigarettes, acquiring sexually transmitted diseases and having early repeat pregnancies; and improved parenting skills. Pregnant drug using women will be identified in the prenatal clinics of Boston City Hospital and Neighborhood Health Centers, through the "Baby Van"program, a neighborhood outreach program to identify pregnant women not enrolled for prenatal care, drug addiction treatment programs and the Alcoholism and Drug Abuse Hotline. Comprebensive day treatment, a pattial hospitalization model, in which patients attend a variety of proqrams at the center for several hours per day and at least three days per week at a neighborhood based center affiliated with the Harvard St. Neighborhood Health Center which is located in the inner city in an area where illicit drug use is a major problem. The center would be open in the evening hours and would serve as a haven for patients to socialize in a drug free environment. Drop in crisis intervention would be available along with scheduled therapy sessions (individual and group). Prenatal care would be provided on site. Prenatal childbirth classes and Postnatal Infant Early Intervention programs would be available on site. Patients would also have access to other programs at the Harvard St. Center. To determine whether maternal participation in the above comprehensive treatment progran will result in improved child outcomes for both the treatment and control groups will be assessed in the Neonatal Foilow Up Program at the Boston City Hospital and will involve standardized measurements of physical growth, health and health care utilization, neurodevelopmental functioning, and socio-affective development over the two years of life (birth,1,4,8,12,18, and 24 months of age).